Depressing reagent for mineral flotation and method for its employment

ABSTRACT

A depressing reagent for the flotation of minerals which is added to the pump to be treated in order to prevent the untimely rise, in the foam, of sterile minerals, characterized by the fact that it is made up of an alginate.

United States Patent 1191 1111 3,844,412

Robert Oct. 29, 1974 DEPRESSING REAGENT FOR MINERAL 1,906,029 4/1933 Weinig 209/167 FLOTATION AND METHOD FOR ITS 5 232,393 i322 gi y woo EMPLOYMENT 2,263,552 1 1/1941 Anderson [76] Inventor: Dominique Robert, 44, Boulevard 2, l7,4l 1943 h l on della Liberation 94-Vincenne 2,327,408 8/1943 E1118 France 2,341,046 2/1944 Kirby 2,466,995 4/1949 McMurray 1. [22] Filed: Nov. 22, 1972 2,633,240 3/1953 Bishop pp No: 308,874 3,009,570 11/1961 Lancaster 209/166 X Related US. Application Data I OTHER PUBLICATIONS [63] Continuation of Ser. No. 49.956, June 25, 1970, Encyclopedla of Chem' Tech- 1965 VOL 771-774. abandoned.

[30] Foreign Application Priority Data Primary Examiner-Robert p June 25, 1970 France 69.21317 Aitorney Agent or Flrmfisughrue Rothwell Mlon Zmn & Macpeak [52] US. Cl. 209/166 511 Int. Cl B03d 1/02 [57] ABSTRACT [58] Field of Search 209/166, 167 A depressing reagent for the flotation of minerals which is added to the pump to be treated in order to [56] References cued preventthe untimely rise, in the foam, of sterile min- UNITED STATES PATENTS erals, characterized by the fact that it is made up of an 1,499,872 7/1924 Price 209/167 X g 1,632,419 6/1927 Simpson 209/166 1,741,028 12/1929 Koenig 209/166 9 Clams D'awmgs DEPRESSING REAGENT FOR MINERAL FLOTATION AND METHOD FOR ITS EMPLOYMENT This application is a continuation of application Ser. No. 49,956, filed 6/25/70 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a depressing reagent for the flotation of minerals and to a method for its employment.

2. Description of the Prior Art It is known, in mineral flotation processes, to use a body called the collector, which is mixedin with the ground mineral and which is in suspension in water or brine, and which is intended, in the foam formed in the course of flotation, to cause the valuable element which is to be recovered and which is contained in the mineral to rise to the top (direct flotation), or sometimes impurities which are thus more easily eliminated (inverse flotation). Among the various types of collectors are anionic collectors, which present a free negative charge in solution (for example, fatty acids); cationic collectors, which present a free positive charge in solution (for example, aminated fat chains); and also nonionic collectors (for example, hydrocarbons).

Most of the time, the collector cannot be used by itself because it also involves the risk of bringing to the top, in the foam, a more or less large percentage of sterile mineral. To prevent this, the collector may be used together with a body called a depressing reagent. Among the most usual depressing reagents are sodium silicate, tannin, dextrin, certain metallic salts, etc.

The function of the depressing reagent, in direct flotation processes, is thus to prevent the untimely rise, in the foam, of a certain number of sterile minerals which would come up, without contaminating the valuable element which is to be recovered.

The present invention concerns such a depressing reagent whose effect, in many cases, is definitely superior to the conventional depressing reagents known to date; this effect is expressed by an improvement in the content of concentrates for a given recovery, and vice versa.

SUMMARY OF THE INVENTION The present invention provides a depressing reagent for the flotation of minerals which is added to the pulp to be treated in order to prevent the untimely rise. in the foam, of sterile minerals, characterized by the fact that it is made up of an alginate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The alginate employed in the present invention is an active colloid which is placed in solution (dissolved) on the basis of known elements in certain algae, which can be sold in the form of flour, or it can be produced artificially.

This invention also concerns a mineral flotation process in which a valuable element is separated from a gangue of sterile substances (refuse) by means of an anionic or cationic collector, characterized by the fact that an alginate is added to the treated pulp, as a depressing reagent, in order to depress the sterile minerals which are difficult to depress and which do not necessarily constitute the largest portion of the refuse.

The alginate, added to the pulp, may be in the form of a product with a high degree of purity but it can also be in the form of a solution together with an inactive phase resulting from the processing of the alginate (e.g., hemicellulose, in the case of a processing using algae through the action of an alkali).

Among the sterile materials which are difficult to depress and with respect to which the depressing reagent according to the present invention proved itself to be particularly effective are: calcite, dolomite, talc, chlorite, barite, and all sterile materials which occur in the form of ultrafme materials or slime (smaller than microns).

The depressing reagent is conditioned with the mineral in pulp form for several minutes without interfering with the employment of other possible regulating reagents (adjustment of the pH, for example), after which the collector, accompanied by a foaming agent or a possible sulfurating agent, is added.

Below are described several nonrestrictive examples for the application of a depressing reagent according to the present invention for the flotation of various minerals. The depressing reagent used in these tests is known under the commercial name of Sobragene," which is made up of algae powder, these algae containing alginic acid. More specifically, Sobragene is a powder of vegetable origin and is sold by Societe Bretonne de Produits Chimiques et Pharmaceutiques, a French corporation. As is known, alginates are hydrophile colloids extracted from various sea algae. It. is also known that alginic acid and its derived substances are obtained from algae according to patented methods which allow one to obtain products of high purity without hemicellulose, organic matters and mineral salts. Therefore, Sobragene" is a powder of any algae containing alginic acid and hemi-cellulose. 1. Concentration of malachite with fatty acid: siliceous gangue with small quantities of calcite, dolomite, phyllosilicates; depression of these annexed minerals and quartz slimes; 2. Concentration of scheelite with fatty acids in the case of calcitic, schistose, or other gangues;

3. Concentration of chromite with fatty acids: depression of slimes of serpentine and calcite;

4. Concentration of fluorine with fatty acids: depression of calcite and barite as well as gypsum, strontianite, celestine and witherite;

5. Concentration of disthene (cyanite, andalousite) with fatty acids:depression of miscellaneous slimes;

6. Concentration of sulfides (or of oxides after sulfuration) of Pb, Zn Cu, and of precious metals with Xenthates or with dithiophosphates: control of primarily carbonated and silico-aluminous gangues (talc, chlorite, sericite, clays) and carbonaceous gangues (gold minerals). The depressing action on the sulfides or the various valuable minerals may appear when the dose of Sobragene is excessive. This excess will depend not on the absolute value of the dose but on the excess of depressant with respect to the quantity necessary for the depression of the gangue (the difference between the doses for the same deslimed or nondeslimed mineral may be as much as 500 g/t).

7. Flotation of patassium with amines: depression of clays;

8. Flotation of zinc-oxide-containing minerals with amines: depression of calcitic barytic gangues and sodium carbonate or silicate and in certain cases, the

possibility of floating in the presence of slimes, provided the proportion of clay does not exceed percent;

9. Purification of glass and ceramic products: depression of clay and certain silico-aluminates (phyllosilicates in general and talc, or chlorites, for example);

10. Flotation in hard water: improvement of water quality by precipitation of alkaline earth and miscellaneous metallic ions.

The following examples further illustrate the process of the present invention.

In the particular case of the flotation of fluorine in the presence of an anionic collector of the family of fatty acids of derivatives thereof (soap of tall oil in the examples given below, or sulfonates of petroleum, hydrolyzed glycerides, oleic, linoleic acids, etc), the following results were obtained in non-deslimed pulp.

EXAMPLE 1 From an 80 percent CaF and percent CaCO mineral (calcite), ground to a size below 200 microns, conditioned with 1 kg/t of sodium silicate at 36B, and floated with 250 g/t of collector, a concentrate of fluorine at 84 percent CaF was obtained.

EXAMPLE 2 From the same calcitic mineral as in Example 1 above with 200 g/t of Sobragene added thereto (a depressing reagent according to the present invention), whose active principles are solubilized as indicated hereinbelow and with the same collector dosage, a 94 percent'CaF concentrate, in a single flotation stage, with the same fluorine yield was obtained.

EXAMPLE 3 From an 80 percent CaF and 20 percent BaSO mineral (barite), ground to below 200 microns, with the same reagents as in Example 1 above, an 84.5 percent CaF concentrate was obtained.

EXAMPLE 4 From the same barytic mineral as in Example 3 above, with 200 g/t of Sobragene added thereto same process as in Example 2 above), a 97 percent CaF concentrate with the same fluorine yield was obtained.

In the particular case of the flotation of pyrochlore, in the presence of an appropriate cationic collector (especially distearylamine acetate), the following results were obtained (in terms of deslimed pulp).

EXAMPLE 5 When only 90 g/t of collector (known by the brand name of Dinoramac S" or "Duomac T") was employed per ton of mineral treated, a first floated concentrate having a Nb O (valuable element) content of 2.10 percent was obtained, for a by-weight yield of 32.9 percent (weight of floated concentrate with respect to the total weight of mineral) and a metallurgical yield of 100 percent, that is to say, the entire valuable element (that is, niobium) of the pulp was recovered in the floated concentrate.

EXAMPLE 6 When 1 20 g/t of Dinoramac S and 150 g/t of Sobragene were added to the same pulp as in Example 5,

wherein the active principles were solubilized as indicated hereinbelow (i.e., a depressing reagent according to the present invention), a floated concentrate having an Nb O content of 2.61 percent was obtained, for a by-weight yield of 26.4 percent and a niobium yield of percent.

In other words, the addition of the depressing reagent according to the present invention provides for a considerable increase in the content of the floated concentrate in terms of the valuable element, a content which ranges from 2.1 percent to 2.6 percent (without valuable element loss).

Additional examples of implementing the flotation method according to the present invention are shown below; specifically, the application of Sobragene to the treatment of a copper mineral from Katanga. The mineral contains 8.50 percent copper, and most of the copper occurs in the form of malachite and there is also a small amount.of chrysocolla which cannot be recovered by flotation. The mineral is ground to a size of less than 250 microns and sweetened water is added to the extent of 40 percent solids, in a laboratory flotation machine. The first test is performed with the conventional sodium silicate formula as described below.

EXAMPLE 7 In a first test, 1,000 grams per ton of sodium carbonate plus ],l00 grams per ton of sodium silicate were conditioned for 10 minutes. After this conditioning, 600 grams per ton of a collector (which is a tall oil soap) was added. The roughcast gives a concentrate which is withdrawn in a finishing stage in the presence of 100 grams per ton of sodium silicate. A finished concentrate titering at 25.90 percent'copper with a copper yield of only 41.5 percent is obtained. A second test is performed with sodium silicate added in a smaller dosage so as to raise the copper yield, resulting in the following roughcast: 1000 grams per ton of sodium carbonate plus 800 grams per ton of sodium silicate were conditioned for 10 minutes. Flotation was performed with the same dosage of 600 grams per ton of fatty acid. The roughcast concentrate is withdrawn in the presence of 100 grams per ton of sodium silicate and a finished concentrate titering at 19.64 percent copper with a yield of 68.8 percent was obtained.

EXAMPLE 8 tained utilizing sodium silicate but with a yield that was greatly improved with respect to everything obtained from the sodium silicate.

In the following examples, wolframite is treated, containing 1.8 percent W0 in a rock consisting of schist, tourmaline, and clay.

In all of the examples described below, 200 grams per ton of a fatty acid collector were employed in a solution which is diluted to the extent of 20 percent solids, with sweet water.

EXAMPLE 8 The results obtained with the conventional formula using sodium silicate are as follows. In the first test:

Carbonate: 3 kilograms per ton, silicate: l kilogram per ton, processed for 10 minutes. Roughcase concentrate with 7.50 percent W 52.] percent W0 yield contained in the mineral.

Another test was performed with sodium silicate and produced results of the same kind: 3 kilograms per ton of sodium carbonate and L5 kilograms of sodium silicate as against l kilogram in the first test. Concentrate with 8.02 percent W0 yield 52.6 percent.

If the method of this invention is employed, the results can be improved in a spectacular fashion, as shown in Example 9.

EXAMPLE 9 With 3 kilograms per ton of sodium carbonate and 400 grams per ton of Sobragene, solubilized in sodium, an 8.20 percent concentrate of W0 was obtained with a yield of 81.5 percent.

EXAMPLE 10 In another test, the Sobragene solubilized with sodium as in Example 9 was replaced by Sobragene solubilized with sodium carbonate, with the following results: 3 kilograms of carbonate per ton, 400 grams of Sobragene per ton. Concentrate 8.25 percent W0 yield 76.0 percent.

EXAMPLE ll Likewise, by employing Sobragene solubilized in sodium carbonate at a rate of 600 grams per ton, instead of 400 as in Example 10, an 8.33 percent W0 concentrate results, with a yield of 70.8 percent.

Thus, the replacement of the sodium silicate by Sograbene regardless of whether Sobragene solubilized with sodium or Sobragene solubilized with sodium carbonate is employed-results in an improvement in the W0 content of the roughcast concentrates and a spectacular improvement in the recovery of the valuable element.

The solubilization of the active principles of Sobragene (alginates) can be obtained by mixing the algae flour with a solution of 40 g/l of sodium carbonate, in a flour: solution rate of 1:10, for about 30 minutes, at a temperature of 50-60"C.

The solubilization of the active principle may also be achieved by mixing the algae flour with sodium or with any other alkali or salts thereof, provided the alginate thus formed is soluble in water.

The concentration of alkalis indicated here was found to produce the best results, but it is possible to accept certain variations, and heating to a temperature of from 50 to 60 percent of 50-60C can be compensated for by providing a longer mixing time.

The paste obtained is then diluted so as to bring about easy fluidity for its mixture with the mineral pulp.

increase in the yield of the valuable element being recovered in the course of the flotation of minerals in which a valuable mineral is separated from a gangue by means of an anionic, cationic or nonionic collector, using the method of the present invention, characterized by the fact that a depressing reagent is added to the treated pulp. The depressing reagent may comprise a natural alginate, or alginic acid solubilized by the addition of an alkali which solubilizes it in the form of a salt of an alkaline ion, for example, Na, K, NH etc., and/or Mg, or a powder of an algae, containing alginic acid incorporated in a solution containing an alkaline ion, for example, Na, K, Nl-l etc., and/or Mg, or a polymer produced artificially from d-mannuronic acid,

either to depress the sterile minerals which are difficult to depress and which do not necessarily constitute the largest portion of the refuse (direct flotation method), or to depress the valuable element and to collect the foam containing the mineral to be rejected (inverse flotation method).

The amount of alginate to be added to the pulp varies from 50 to 600 grams per ton of mineral involved in the flotation process. The amount increases as a function of the percentage by weight of the minerals that are capable of fixing the colloid on their surface and as a function of the surface of the grains of these minerals.

What is claimed is:

l. In a mineral flotation method in which a valuable mineral is separated from a gangue of sterile matter containing carbonates, or sulfates of alkaline earth metals or phyllosilicates, or quartz slimes in the form of a treated pulp by means of a collector selected from the group consisting of anionic and nonionic collectors, the improvement which comprises adding to the treated pulp as a depressing reagent an unpurified algae powder selected from the group consisting of a natural alginate, alginic acid solubilized by the addition of an alkali which solubilizes said alginic acid in the form of the salt of the alkaline ion, an algae powder containing alginic acid incorporated in a solution containing an alkaline ion, and a polymer produced artificially from dmannuronic acid whereby said algae powder is added either to depress the sterile matter which is difficult to depress, or to depress the valuable minerals and to collect a foam containing the sterile matter to be rejected.

MA method as in claim 1 wherein. said mineral is se-.

lected from the group consisting of malachite, scheelite, wolframite. chromite, calcium fluoride, disthene, sulfides of lead, of zinc, of copper, and of precious metals, bauxite, calcium phosphates, iron minerals, oxidized minerals of cobalt, or cassiterite, which do-not undergo the depressing action of the reagent,the rea gent dose being kept below 1000 g/t of mineral involved in the flotation.

5. A method as in claim 1, wherein said alkaline ion is at least one member of the group consisting of Na, K, NH, and Mg.

6. A method as in claim 1, wherein said algae powder is a powder containing alginic acid and hemicellulose and sold under the trademark Sobragene.

7. ln a mineral flotation method in which a valuable 'mineral is separated from a gangue of sterile matter aqueous alkali solution, whereby the algae powder depresses the sterile matter which is difficult to depress or depresses the valuable minerals thereby collecting a foam containing the minerals to be rejected.

8. The method as in claim 7 wherein said algae powder is mixed with an aqueous sodium carbonate solution containing about 40 g/l of sodium carbonate in an algae powder: sodium carbonate solution weight ratio of about 1:10 at a temperature of from 50 to C.

9. The method as in claim 7 wherein the alkaline ion in said aqueous alkali solution is at least one member selected from the group consisting of sodium, potassium, ammonium, and magnesium. l 

1. IN A MINERAL FLOTATION METHOD IN WHICH A VALUABLE MINERAL IS SEPARATED FROM A GANGUE OF TERILE MATTER CONTAINING CARBONATES, OR SULFATES OF ALKALINE EARTH METALS OF PHYLLOSILICATES, OR QUARTZ SLIMES IN THE FORM OF A TREATED PULP BY MEANS OF A COLLECTOR SELECTTED FROM THE GROUP CONSISTING OF ANIONIC AND NONIONIC COLLECTORS, THE IMPROVEMENT WHICH COMPRISES ADDING TO THE TREATED PULP AS A DEPRESSING REAGENT AN UNPURIFIED ALGAE POWDER SELECTTED FROM THE GROUP CONSISTING OF A NATURAL ALGINATE, ALGINIC ACID SOLUBILIZED BY THE ADDITION OF AN ALKALI WHICH SOLUBILIZES SAID ALGINIC ACID IN THE FORM OF THE SALT OF THE ALKALINE ION, AL ALGAE POWDER CONTAINING ALGINIC ACID INCORPORATED IN A SOLUTION CONTAINING AN ALKALINE ION, AND A POLYMER PRODUCED ARTIFICIALLY FROM D-MANNURONIC ACID WHEREBY SAID ALGAE POWDER IS ADDED EITHER TO DEPRESS THE STERILE MATTER WHICH IS DIFFICULT TO DEPRESS, OR TO DEPRESS THE VALUABLE MINERALS AND TO COLLECT A FOAM CONTAINING THE STERILE MATTER TO BE REJECTED.
 2. A method as in claim 1 wherein, all of said sterile matter being in the form of ultra-fine particles having dimensions of less than 80 microns, and according to which the quantity of alginate used is between 50 and 600 grams per ton of mineral involved in the flotation process.
 3. A method as in claim 2, wherein said phyllosilicates are selected from the group consisting of clay, chlorites, talc and the like.
 4. A method as in claim 1 wherein said mineral is selected from the group consisting of malachite, scheelite, wolframite, chromite, calcium fluoride, disthene, sulfides of lead, of zinc, of copper, and of precious metals, bauxite, calcium phosphates, iron minerals, oxidized minerals of cobalt, or cassiterite, which do not undergo the depressing action of the reagent, the reagent dose being kept below 1000 g/t of mineral involved in the flotation.
 5. A method as in claim 1, wherein said alkaline ion is at least one member of the group consisting of Na, K, NH4 and Mg.
 6. A method as in claim 1, wherein said algae powder is a powder containing alginic acid and hemicellulose and sold under the trademark ''''Sobragene.''''
 7. In a mineral flotation method in which a valuable mineral is separated from a gangue of sterile matter containing carbonates or sulfates of alkaline earth metals or phyllosilicates or quartz slimes in the form of a treated pulp by means of a collector selected from the group consisting of anionic and nonionic collectors, the improvement which comprises adding to the treated pulp as a depressing reagent an algae powder containing alginic acid and hemi-cellulose, said algae powder being added in the form of an alkali solution of an alginic acid salt formed by adding the algae powder to an aqueous alkali solution, whereby the algae powder depresses the sterile matter which is difficult to depress or depresses the valuable minerals thereby collecting a foam containing the minerals to be rejected.
 8. The method as in claim 7 wherein said algae powder is mixed with an aqueous sodium carbonate solution containing about 40 g/l of sodium carbonate in an algae powder: sodium carbonate solution weight ratio of about 1:10 at a temperature of from 50* to 60*C.
 9. The method as in claim 7 wherein the alkaline ion in said aqueous alkali solution is at least one member selected from the group consisting of sodium, potassium, ammonium, and magnesium. 